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    Microvesicles are generated by the outward budding and fission of membrane vesicles from the cell surface. Recent studies suggest that microvesicle shedding is a highly regulated process that occurs in a spectrum of cell types and, more frequently, in tumor cells. Microvesicles have been widely detected in various biological fluids including peripheral blood, urine and ascitic fluids, and their function and composition depend on the cells from which they originate. By facilitating the horizontal transfer of bioactive molecules such as proteins, RNAs and microRNAs, they are now thought to have vital roles in tumor invasion and metastases, inflammation, coagulation, and stem-cell renewal and expansion. This Commentary summarizes recent literature on the properties and biogenesis of microvesicles and their potential role in cancer progression.
    Microvesicle
    Tumor progression
    Citations (891)
    Cells secrete various membrane-enclosed microvesicles from their cell surface (shedding microvesicles) and from internal, endosome-derived membranes (exosomes). Intriguingly, these vesicles have many characteristics in common with enveloped viruses, including biophysical properties, biogenesis, and uptake by cells. Recent discoveries describing the microvesicle-mediated intercellular transfer of functional cellular proteins, RNAs, and mRNAs have revealed additional similarities between viruses and cellular microvesicles. Apparent differences include the complexity of viral entry, temporally regulated viral expression, and self-replication proceeding to infection of new cells. Interestingly, many virally infected cells secrete microvesicles that differ in content from their virion counterparts but may contain various viral proteins and RNAs. For the most part, these particles have not been analyzed for their content or functions during viral infection. However, early studies of microvesicles (L-particles) secreted from herpes simplex virus-infected cells provided the first evidence of microvesicle-mediated intercellular communication. In the case of Epstein-Barr virus, recent evidence suggests that this tumorigenic herpesvirus also utilizes exosomes as a mechanism of cell-to-cell communication through the transfer of signaling competent proteins and functional microRNAs to uninfected cells. This review focuses on aspects of the biology of microvesicles with an emphasis on their potential contributions to viral infection and pathogenesis.
    Citations (367)
    Cells release multiple, distinct forms of extracellular vesicles including structures known as microvesicles, which are known to alter the extracellular environment. Despite growing understanding of microvesicle biogenesis, function and contents, mechanisms regulating cargo delivery and enrichment remain largely unknown. Here we demonstrate that in amoeboid-like invasive tumour cell lines, the v-SNARE, VAMP3, regulates delivery of microvesicle cargo such as the membrane-type 1 matrix metalloprotease (MT1-MMP) to shedding microvesicles. MT1-MMP delivery to nascent microvesicles depends on the association of VAMP3 with the tetraspanin CD9 and facilitates the maintenance of amoeboid cell invasion. VAMP3-shRNA expression depletes shed vesicles of MT1-MMP and decreases cell invasiveness when embedded in cross-linked collagen matrices. Finally, we describe functionally similar microvesicles isolated from bodily fluids of ovarian cancer patients. Together these studies demonstrate the importance of microvesicle cargo sorting in matrix degradation and disease progression. Cells shed various types of vesicles differing in size and content. Here the authors show that cancer cells utilize VAMP3-mediated traffic to deliver MT1-MMP to surface microvesicles and facilitate amoeboid-like cell invasion, with VAMP3-containing vesicles also found in body fluids of cancer patients.
    Microvesicle
    Tetraspanin
    Citations (166)
    Microvesicle biogenesis is a highly regulated process. Aberrant release of microvesicles from cancer cells have been associated with their invasiveness and prognosis. However, the mechanism of aberrant release remains poorly understood. Herein, we found that hepatocellular carcinoma cells shed more microvesicles than normal hepatocytes and miR-200a were shown to inhibit the release of microvesicles in hepatocellular carcinoma cells. Then, we confirmed that miR-200a might target Gelsolin and change cytoskeleton to regulate microvesicles secretion. Further miR-200a may inhibit the proliferation of adjacent cells by inhibiting the release of microvesicles. Collectively, our findings indicate that miR-200a regulated the microvesicle biogenesis involved in the hepatocellular carcinoma progression.
    Microvesicle
    Gelsolin
    Exosome
    Citations (27)